12 Nebraskaland • April 2022
IN THE FIELD
Hunter opportunity is one of the many
considerations that go into developing
waterfowl hunting season recommendations. For
Nebraska waterfowl hunters, that largely means
recommending hunting season dates that overlap
with the highest concentrations of birds in the
state. Although Game and Parks does not have
a formal waterfowl survey during the fall, duck
migration estimations have improved through the
use of eBird.
The Cornell Lab of Ornithology in Ithaca, New
York, developed the eBird platform to offer birders
a way to store and organize birding media, species
lists, counts for single birding events, and "life
lists"— complete lists of every bird species seen
by an individual — at county, state, national and
global scales. Since the release of eBird in 2002,
birders have contributed more than 60 million
checklists containing over half a billion bird
sightings.
A team of scientists at the Cornell Lab used eBird
observations from January 2006 – December 2020,
along with data on habitat, weather and birder
experience, to predict the relative abundance of a
species in a given location for each week through
the year. Recently, the Nebraska Game and Parks
Commission used these data to estimate the
migration chronology of ducks.
We used known life histories to group 13 of the
most common duck species found in Nebraska,
including early migrants: blue-winged teal and
wood ducks; mid-season migrating dabbling
ducks: northern pintail, American wigeon,
northern shoveler, green-winged teal and gadwall;
mid-season migrating diving ducks: canvasback,
redhead, ring-necked duck, lesser scaup and
common goldeneye; and late migrants: mallards.
At the statewide level, relative abundance of
blue-winged teal and wood duck numbers show
steep declines through October, with mallard
numbers peaking in December. Weekly relative
abundance for all species demonstrated two peaks
in migration that predominately represented
mallards and other dabbling ducks. We repeated
this process to estimate the timing of autumn
duck migration in each of the four duck hunting
zones in Nebraska. Average migration chronology
was one data stream used to inform waterfowl
hunting season date recommendations to
maximize opportunities for duck hunters.
Visit ebird.org to learn about collecting and
reporting birding data. Visit ebird.org/science/
status-and-trends/ to learn more about how
weekly relative abundance is estimated.
ESTIMATING DUCK MIGRATION
By Cynthia Anchor, Waterfowl Biologist
